The present invention relates generally to power coupling devices such as power summers, power dividers and star couplers, and more particularly to fiber optic power coupling devices.
Fiber optic power summers, power dividers and star couplers utilizing fused single mode fibers are commercially available. However, uniformity, modal dependence and insertion loss are continuing problems. In addition, it is not possible to sum single mode fiber outputs because of interference effects, particularly if the signals are close in frequency.
In my U.S. Pat. No. 4,577,924, an optical RF bandpass filter was described which consisted of a multimode optical fiber segment having reflecting mirrors on each end so that it functioned as a resonant cavity with respect to a particular modulation frequency when the length of the fiber was equal to one-half of the modulation wavelength of light injected into the fiber. This type of filter may be used in various signal processing applications, for example in electronic intelligence receivers, data busses, fast frequency hopping modems, and so on.